1. Field of the Invention
This invention pertains to a method of connecting the liquid and suction tubes on a refrigeration system which has the evaporator located remotely from the condenser such that the liquid tube is enclosed inside of the suction tube.
2. Description of the Related Art
Refrigeration systems which have the evaporators located remotely from the compressor and condenser have the liquid and suction tubes piped separately to the evaporators. In some systems, which have several evaporators located in different locations, the liquid and suction tubes are run individually to the evaporating units. In other instances the liquid and vapor tubes are connected tree fashion, i.e., they branch off from main liquid and vapor trunks. In both instances, multiple tubes are plumbed requiring significant labor and materials costs.
The cost of connecting the remote evaporators for a typical supermarket can exceed $100,000. The installations require the skill of journeymen pipe fitters and welders. The welding/brazing of the tubing (usually copper) also causes oxidation of the inside of the tubes, which is undesirable. To prevent this oxidation, an installer is required to purge nitrogen gas through the system while welding the tubes adding further cost to the installation. Reduction of the number of tubes, and resultant welds/brazes to be made is therefore of interest.
For systems in which the liquid tubes are sub-cooled, the liquid tubes require insulation to prevent condensation and energy loss, again adding cost.
Refrigerant loss is also a major problem in refrigeration and air conditioning systems. The loss of refrigerant in a liquid tube represents a potential of larger leakage than in the suction tube because of the more than 100 times higher density of the refrigerant in the liquid tube than in the suction tube. Such refrigerant loss due to leakage can be costly, and reducing the number of tubes as well as the number of welds/brazes (often the point of leakage) would be beneficial in reducing costs. The loss of refrigerant into the atmosphere has also become a significant problem to the extent that local municipalities have enacted laws governing the control and safety issues of refrigerants.
Finally cooling the liquid in the liquid tube can improve system efficiency. Therefore, if the liquid tube were installed inside the suction tube (which contains cool vapor) it would be cooled, and the cost of operation could be reduced. The current invention goes beyond the teaching in U.S. Pat. No. 4,147,937 which discloses enclosing only the capillary tube of refrigeration system for the purpose of sub-cooling by installing the entire liquid line within the suction line to achieve the further objectives and benefits described herein.
The current invention is therefore, a design for connecting liquid and suction tubes from a compressor(s) to an evaporator(s) by installing the liquid tube(s) inside the suction tube(s), thereby simplifying installation, cooling the liquid tube, and minimizing the deleterious aspect of leaks in the liquid tube by containing any such leaks in the liquid tube to inside the suction tube and not to the atmosphere.
One of the objectives of the current invention is to reduce the probability of a leak occurring in the liquid tube(s).
Another objective of the current invention is to prevent a refrigerant leak to the atmosphere if a leak occurs in the liquid tube(s).
Another objective of this invention is to reduce the cost of a piping installation by eliminating the insulation on a liquid tube(s).
Another objective of this invention is to reduce the cost of a piping installation by eliminating the need to mount the liquid tube(s) to a structure.
Another objective of this invention is to reduce the cost of a piping installation by eliminating the need to us e high pressure rated tubing for the liquid tube when the liquid line pressure is reduced.
Another objective of this invention is to further sub-cool liquid arriving at the expansion valve.
Another objective of this invention is to boil liquid returning in the suction tube so as to prevent damage to the compressor.